Model compounds for hemoglobin and related hemoproteins will be prepared and the effect of their structure on the dynamics of reaction with dioxygen, carbon monoxide, and isonitriles studied. Cyclophane heme compounds displaying distal side steric effect will be studied by structural, spectroscopic and kinetic methods in order to define the nature of the distal side steric effect. New ortho-substituted tetraphenylheme derivatives will be prepared and their interaction with CO and dioxygen studied in order to define the new phenomenon of heme rigidity and its effect on ligand binding. Synthetic heme compounds already demonstrated to show cooperativity and pH-dependent binding will be studied by computer modeling and by titration and kinetic methods. Flash photolysis of heme complexes will be studied by FTIR methods to obtain flash IR spectra of unstable intermediates. Similar studies by flash resonance Raman spectra will be undertaken in order to describe the relaxation processes occurring in protein-free active sites. This study will define those characteristics of heme compounds and their environment which control the varied reactivities of such hemes in hemoproteins. This information will provide the means of understanding the cooperativity in hemoglobin and other biomolecular reactions and will allow synthetic oxygentransporting materials, for use as blood substitutes, to be prepared.